More than 10,000 people have been found to have registered more than once in the vote for the upcoming elections.
Report says the National Elections Commission reported the matter to judicial officials on Tuesday.
Maude Somah, Justice Ministry official, says the ministry is investigating.
Presidential and legislative elections are slated for later this year.
More than 25 candidates are preparing to challenge incumbent President Ellen Johnson Sirleaf.
Liberia was ravaged by civil wars for years until 2003. The country is still struggling to maintain a fragile peace with the help of U.N. peacekeepers.